Methods and systems for a wireless routing architecture and protocol

ABSTRACT

The present invention provides a method for generating routing paths in a multi-hop network. The multi-hop network includes a base station, at least one relay station, and at least one non-relay mobile station. The routing paths are paths between the base station and the at least one non-relay mobile station via the at least one relay station. The base station broadcasts a path discovery message (PDM) including a path list with a starting point of the path list being the base station. Each of the relay stations receives the PDM and updates the PDM by adding their own respective node identifier to the path list and broadcasting the updated PDM. The PDMs eventually reach the non-relay mobile station. The non-relay mobile stations reply to the base station by sending the base station the updated path list between the base station and the non-relay mobile station. In some embodiments the base station or the at least one non-relay mobile station acting as a source node sends a dynamic service (DSx) message including an end-to-end path list to an end of path destination. The relay stations use the path list to forward the message between the source node and the end of path destination. In some implementations the multi-hop network operates in a manner that is consistent with any one of: IEEE 802.16, IEEE 802.16d, and IEEE 802.16e.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 11/481,825 filed Jul. 7, 2006, which claims thebenefit of U.S. Provisional Patent Application No. 60/730,763 filed onOct. 27, 2005, both of which are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

The invention relates to routing for wireless signal transmission.

BACKGROUND OF THE INVENTION

WiMAX is defined as “Worldwide Interoperability for Microwave Access” bythe WiMAX Forum, which was formed in April 2001 to promote conformanceand interoperability of the IEEE 802.16 standard. WiMAX is described as“a standards-based technology enabling the delivery of last milewireless broadband access as an alternative to cable and DSL.”

One aspect of the standard provides a simple Point-to-Multi-Point (PMP)architecture. The PMP architecture includes a base station (BS)communicating over a single hop to one or more wireless mobile stations(MS). FIG. 1A shows an example of a PMP architecture in which BS 50 isin communication with MS 52 and MS 54. In an ideal case, conventionalPMP transmission allows for a 50 km hop and transmission rates ofapproximately 30 Mbps in the direction from BS to MS and 17 Mbps in thedirection from MS to BS. To provide suitable transmission over thesingle hop, a BS having a tall antenna with a good line of sight to theMS is typically required.

The current version of IEEE 802.16d also defines a mesh architecture. Ina mesh network each node only transmits as far as an adjacent node. In amesh network nodes can transmit data from nearby nodes to nodes that aretoo far away to reach in a single hop or do not have clear line ofsight, resulting in a network that can span large distances. Thisintroduces complexity to network control and resource scheduling. Thecurrent version of the IEEE 802.16d mesh network architecture isconsidered to be “connection-less”. Connection-less mode transmission isa transmission format in which packets are provided with headerinformation sufficient to permit delivery of the packets withoutadditional instructions.

The mesh mode as it is currently defined in the standard is not entirelycompatible with the PMP mode due to different frame structures used fortransmission of messages and data in each respective mode. The two modesalso have different procedures for network entry. In addition, the meshmode does not support handoff for mobility of the MS. The mesh mode alsodoes not support OFDMA at PHY layer.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a methodfor execution in a multi-hop network comprising a base station and atleast one relay station for generating routing paths between the basestation and at least one non-relay mobile station, the methodcomprising: the base station broadcasting over a first hop a pathdiscovery message (PDM) including a path list comprising a nodeidentifier for the base station; each relay station of the at least onerelay station; receiving the PDM that was broadcast over a precedinghop, the PDM including the path list defining all preceding hops; addinga node identifier of the relay station to generate an updated path listin the PDM; and broadcasting a PDM including the updated path list overa subsequent hop; the base station receiving a reply from a given one ofthe at least one non-relay mobile station, the reply comprising arespective path list including node identifiers of all stations in arouting path between the base station and the non-relay mobile stationinclusive, the reply being routed via relay stations identified in therespective path list.

In some embodiments when a non-relay mobile station of the at least onenon-relay mobile station receives multiple PDMs, each having a differentpath list, from different relay stations, the at least one non-relaymobile station: determines which one of the multiple PDMs has apreferred path list based on at least one criterion characterizing thepath lists of the multiple PDMs; and selects the PDM with the preferredpath list to use as a routing path between the base station and thenon-relay mobile station.

In some embodiments the at least one criterion is selected from a groupconsisting of: the shortest path between the base station and the atleast one non-relay mobile station; the best determined radioperformance between the base station and the at least one non-relaymobile station; a quality of service (QoS) value, orleast-power-consumed link between the base station and the at least onenon-relay mobile station.

In some embodiments at least one relay station or at least one non-relaymobile station determines whether a generated routing path is valid by:periodically sending a request message to the base station; andreceiving a response to the request message if the routing path is stillvalid.

In some embodiments the method further comprises: the base station or anon-relay mobile station of the at least one non-relay mobile stationsending over a first hop a service flow request message including anend-to-end path list and a connection identifier (CID) that defines theconnection between the base station and the non-relay mobile station;each relay station of the at least one relay station; receiving theservice flow request message that was broadcast over a preceding hop;and determining whether the message is to be forwarded over a subsequenthop or dropped based on the path list and the CID; if the message is tobe forwarded, forwarding the message over a subsequent hop based on thecontents of the path list and the CID.

In some embodiments the method is applied to a wireless networkoperating in a manner that is consistent with any one of: IEEE 802.16,IEEE 802.16d, and IEEE 802.16e.

In some embodiments the base station allocates transmission resources toeach of the at least one relay stations and each of the at least onerelay stations partitions the allocated transmission resources to atleast one subordinate RS.

In some embodiments allocated transmission resources are at least oneof: shared band and time slots with MIMO transmissions, shared band andtime slots with beam-forming transmissions, adjacent band slots withMIMO transmissions, adjacent band slots with beam-forming transmissions,or different sub-channels.

In some embodiments the end-to-end path list is comprised of a list ofentries, the entries each being one of node identifiers or linkidentifiers.

In some embodiments broadcasting a PDM by the base station or arespective relay station further comprises broadcasting anair-link-descriptor for each respective hop.

In some embodiments at least one routing path comprises more than twohops.

According to a second aspect of the invention, there is provided amethod for execution in a multi-hop network comprising a base stationand at least one relay station for message forwarding based on knownrouting paths between the base station and at least one non-relay mobilestation, the method comprising: the base station or a non-relay mobilestation of the at least one non-relay mobile station sending over afirst hop a service flow request message including an end-to-end pathlist and a connection identifier (CID) that defines the connectionbetween the base station and the non-relay mobile station; each relaystation of the at least one relay station; receiving the service flowrequest message that was broadcast over a preceding hop; and determiningwhether the message is to be forwarded over a subsequent hop or droppedbased on the path list and the CID; if the message is to be forwarded,forwarding the message over a subsequent hop based on the contents ofthe path list and the CID.

In some embodiments the service flow request message further comprises atransport CID identifying a connection between two stations over asingle hop that can be used to create an entry in a forwarding table fora respective relay station to forward messages between the base stationand the non-relay mobile station.

In some embodiments when the at least one relay station receives aservice flow MAC PDU (media access control protocol data unit) from thedirection of the base station, the relay station uses the CID of the MACPDU to look up the forwarding table to determine whether to furtherbroadcast the MAC PDU in the direction of the non-relay mobile stationor drop the MAC PDU.

In some embodiments when the at least one relay station receives amanagement flow MAC PDU from the direction of the base station, therelay station checks the ownership of the CID in the forwarding table todetermine whether to process the MAC PDU, further broadcast the MAC PDUin the direction of the non-relay mobile station, or drop the MAC PDU.

In some embodiments sending the service flow message comprises includinga node ID list which is a path list that consists of all the stationsalong a selected path between the base station and at least one relaystation and/or the non-relay mobile station.

In some embodiments sending the node ID list comprises sending the nodeID list in a MAC sub-header.

In some embodiments the method further comprises including aair-link-descriptor for a first and subsequent hops in the MACsub-header.

According to a third aspect of the invention, there is provided amulti-hop network adapted for communication with at least one non-relaymobile station, the network comprising: a base station; and at least onerelay station being adapted to receive and forward transmissions betweenthe base station and the at least one non-relay mobile station: wherein:the base station being adapted to broadcast over a first hop a pathdiscovery message (PDM) including a path list with a starting point ofthe path list being the base station; each relay station of the at leastone relay station being adapted to: receive the PDM that was broadcastover a preceding hop, the PDM including the path list defining allpreceding hops; add a node identifier of the relay station to generatean updated path list in the PDM; and broadcast a PDM including theupdated path list over a subsequent hop; and the base station beingfurther adapted to receive a reply from each of the at least onenon-relay mobile station, the reply comprising a respective path listincluding the node identifiers of all stations in the routing pathbetween the base station and the non-relay mobile station, the replybeing routed via relay stations identified in the respective path list.

In some embodiments the base station or a non-relay mobile station ofthe at least one non-relay mobile station sends over a first hop aservice flow request message including an end-to-end path list and aconnection identifier (CID) that defines the connection between the basestation and the non-relay mobile station; each relay station of the atleast one relay station; receives the service flow request message thatwas broadcast over a preceding hop; and determines whether the messageis to be forwarded over a subsequent hop or dropped based on the pathlist and the CID; forwards the message over a subsequent hop based onthe contents of the path list and the CID, if it is determined that themessage is to be forwarded.

In some embodiments at each relay station a priority class identifierassociated with a MAC PDU is used by the relay station to prioritizetransmission order of the MAC PDU.

In some embodiments at least one of the at least one relay stations isone of: a fixed location relay station, a nomadic relay station and amobile relay station.

In some embodiments the multi-hop network operates in a manner that isconsistent with any one of: IEEE 802.16, IEEE 802.16d, and IEEE 802.16e.

According to a further aspect of the invention, there is provided amethod for execution by a non-relay mobile station that is adapted to bein communication with a base station via at least one relay station, thenon-relay mobile station involved with generation of a routing pathbetween the base station and the non-relay mobile station, the methodcomprising: receiving a PDM that originated from the base station andwas broadcast over a preceding hop from at least one relay station, thePDM including a path list defining all preceding hops; adding a nodeidentifier of the non-relay mobile station to the path list to generatean updated path list between the base station and the non-relay mobilestation; and sending the base station the updated path list, the updatedpath list being routed via relay stations identified in the updated pathlist.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theattached drawings in which:

FIG. 1A is a schematic diagram of a point-to-multi-point (PMP) networkarchitecture;

FIG. 1B is a schematic diagram of a multi-hop network architecture foruse with some embodiments of the invention;

FIG. 2 is a schematic diagram of a multi-hop network architectureillustrating base station (BS) oriented route discovery according to anembodiment of the invention;

FIG. 3 is a schematic diagram of a multi-hop network architectureillustrating constraint based dynamic service signaling according to anembodiment of the invention;

FIG. 4 is a schematic diagram of a frame used for Down link (DL) and Uplink (UL) transmission in accordance with some embodiments of theinvention;

FIG. 5 is a schematic diagram of an example of a modified MAC (mediaaccess control) sub-header for use with some embodiments of theinvention; and

FIG. 6 is a signaling flow diagram illustrating operation of themulti-level relay network architecture according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

In some embodiments of the present invention there are providedprotocols for use with a multi-hop network architecture. In someembodiments the multi-hop network architecture is a tree architecture.In some embodiments the multi-hop network architecture is a mesharchitecture.

In the multi-hop architecture, a relay station (RS) is utilized betweena base station (BS) and a mobile station (MS). Therefore, multiple hopsoccur between the BS and MS. Multiple RS may be located between the BSand the MS. In some implementations the multi-hop network architectureis used in addition to the single hop PMP architecture.

The RS may be installed inside of a building (e.g., subway tunnel), on aroof top of a building or a residential house, on an RS tower, on amobile vehicle platform (e.g., trains, buses, ferries), on aerial-basedplatforms, or even possibly carried by soldiers in the battlefield.

Some examples of devices that may be considered to be a MS are acellular telephone, a computer having a wireless modem, and a wirelessenabled PDA (Personal Data Assistants).

In the multi-hop network architecture, there are two types of airinterfaces. A first type of air interface occurs between BS and RS andbetween RS and RS and a second type of air interface occurs between RSand MS. The two air interfaces are either logical (they share the sameradio spectrum) or physical (they may use different radio spectrum).

A first aspect of the invention provides a method for each station(BS,RS,MS) to discover adjacent neighbours automatically and to findrouting paths in a dynamically changing wireless access network. Asecond aspect is managing end-to-end (that is BS to MS, via theintermediate RS, or vice versa) connections, otherwise referred to asdata flow forwarding paths.

A BS-oriented Dynamic Source Routing (DSR) protocol is provided toenable each node (both RS and MS) to automatically generate routingpaths between the BS and themselves. The protocol is considered to beBS-oriented as the BS originates the protocol by broadcasting a pathdiscovery message (PDM). Each RS that receives the message appends itsown identification to the message, which creates a path list and theforwards the message on. Each MS that receives the message sends backthe complete path list to the BS, via the relay stations included in thepath list. In some embodiments the BS-oriented protocol utilizes a DownLink (DL) broadcast mechanism that is a feature of the IEEE 802.16standard, such as a DL-MAP and a centralized radio allocation techniqueof the PMP mode to send the path discovery message.

In some embodiments of the invention, there is provided aconstraint-based signaling protocol for end-to-end connection (data flowforwarding path) management in the multi-hop topology. In someembodiments of the invention, Dynamic Service (DSx) signaling based onIEEE 802.16 is used in conjunction with a determined path list to createand manage data flow forwarding paths.

In some embodiments of the invention new MAC (media access control)layer functions are provided to implement the protocols.

The MAC layer is used to enable features in the physical (PHY) layer inan air interface architecture. A frame is a format used to transmit dataover the air interface between BS and RS and/or MS. An example of aframe structure will be described below with reference to FIG. 4.

BS-Oriented Dynamic Source Routing

Reference to FIG. 2 will now be made in describing the BS-oriented DSRprotocol.

FIG. 2 illustrates an example multi-hop network 200 including a basestation 205. The base station 205 is in communication with two relaystations, namely RS 210 and RS 212. RS 210 is in communication with tworelay stations, RS 220 and RS 222. RS 220 is in communication with twomobile stations, namely MS 230 and MS 232. RS 212 is in communicationwith two relay stations, RS 224 and RS 226. RS 226 is in communicationwith two mobile stations, namely MS 234 and MS 236.

FIG. 2 is one example of such a network. It is to be understood that thenumber of RS and MS in the network is implementation specific.Furthermore, the number of RS between BS and MS can be greater than orless than the two that are shown in FIG. 2.

In operation, BS 205 transmits broadcast messages in a frame structureto RS one hop away from the BS. The frame structure includes multipleMAC messages. The MAC messages include broadcast messages to more thanone MS or messages directed to individual MS. One type of broadcastmessage is a path discovery message, generally indicated at 207. Thepath discovery message 207 includes a connection identifier (CID) forthe message that is referred to as a broadcast CID 208. The broadcastCID 208 is used to indicate a connection to all MS communicating withthe BS. In some embodiments the broadcast CID 208 is an efficient mannerof addressing all MS by utilizing 802.16 PMP downlink transmissioncharacteristics. In some embodiments the broadcast CID is located in aheader of the path discovery message. In some embodiments, the discoverymessage is embedded in 802.16 broadcast control messages such as DL-MAPmessage. A subsequent portion of the path discovery message 207 is apath list 209. The path list 209 when transmitted by the BS 205 includesonly the identification of the BS 205.

RS 212 receives the path discovery message 207 and adds itsidentification to the path list 209, such that updated path list 228 inthe path discovery message 207′ includes BS 205 and RS 212. RS 212 thenbroadcasts the path discovery message 207′ to RS 224 and RS 226. RS 226then repeats this process so updated path list 235 in path discoverymessage 207″ broadcast by RS 226 includes BS 205, RS 212 and RS 226.

In some embodiments, an air-link-descriptor which describes the radiochannel quality information and/or the power consumption of each RS canbe associated with each entry in the path list.

MS 236 receives the path discovery message 207″ and adds its ownidentification to path list 235 resulting in end-to-end path list 244.MS 236 sends a response back to BS 205 in a MAC message 240 with theend-to-end path list 244. The MAC message 240 includes a CID referred toas a management CID 242. The management CID 242 indicates an MS specificconnection related to management of the link between the BS 205 and MS236, as opposed to for example a connection for transport of databetween the BS 205 and MS 236. In some embodiments, this responsemessage with path list may be implemented by utilizing an uplinkuni-cast message according to IEEE 802.16, such as a RNG-REQ (RangingRequest) message.

The preceding description is for discovery of the path route between BS205 and MS 236, but it is to be understood that the same process isoccurring along other path routes in the network. For example, each ofthe RS which receive the path discovery message from the BS in a firsthop, updates the path discovery message by adding their own respectivenode identifier to the path list in the received path discovery message,which initially only contains the BS node identifier. The RS sends theupdated path discovery message over a second hop. After each subsequenthop to either a further RS or a MS, the path discovery message receivedby the further RS or the MS is updated to include the node identifier ofthe respective station.

In some embodiments the MS may receive a path discovery message frommore than one RS. The received path discovery messages each have adifferent path list as they have hopped along different routes to reachthe MS. The MS then makes a decision as to which path list is to beselected and communicates this selection to the BS. In some embodimentsthis decision is made based on the number of the hops in the path list(e.g., the shortest path). In some embodiments this decision is madebased on channel/power information collected from air-link-descriptor(e.g., the better quality or energy saving path).

More generally, a method for generating routing paths in a multi-hopnetwork between a base station and at least one non-relay mobile stationover multiple hops via at least one relay station can be described asfollows. The base station broadcasts a path discovery message (PDM)including a path list in which a starting point of the path list is thebase station. As described above, the PDM may also include the air-linkquality information between the BS and RS. Each relay station of the atleast one relay station receives a PDM over a preceding hop, thereceived PDM including the path list defining all preceding hops. Eachrelay station adds a node identifier of the relay station to generate anupdated path list in the PDM. In some embodiments the relay stationsalso include the associated air-link quality information. Each relaystation then broadcasts the PDM over a subsequent hop. Each of the atleast one non-relay mobile station receives the PDM from a preceding hopand adds a node identifier of the non-relay mobile station to the pathlist to generate an updated path list between the base station and thenon-relay mobile station. Each non-relay mobile station then replies tothe base station by sending the updated path list between the basestation and the non-relay mobile station. In some embodiments for thereplay message, each relay station on the reverse path adds air-linkquality information for each link back to the base station.

In some embodiments the path list is created by using link identifiers,which are links between nodes or stations (BS,RS,MS), as opposed to nodeor station identifiers.

The BS-oriented DSR protocol provided in some embodiments of theinvention includes features for route discovery, route optimization, androute maintenance. Route discovery provides a mechanism for determininga path between the BS and MS via one or more RS as described above.Route optimization provides a mechanism for selecting an optimum routeif more than one route is discovered. Route maintenance provides amechanism for ensuring the routes that have been previously determinedare still valid.

Route Discovery

The BS periodically broadcasts the path discovery message and DLbandwidth availability with a sequence number. The path discoverymessage is transmitted by each RS to reach the respective MS asdescribed above. In some embodiments the path discovery messagetransmitted by the BS is piggybacked on a broadcast management messagesuch as a DL-MAP provided by IEEE 802.16d. In some embodiments theresponse MAC message transmitted by the MS is piggybacked on a RNG-REQ(Ranging request) message as provided by IEEE 802.16d.

Route Optimization

When a MS receives multiple path discovery messages from different airlinks, each having a corresponding path list the MS can select a pathfrom the multiple path discovery messages based on certain criterion.Some examples of selection criteria are a shortest path, a best radioperformance, a QoS path, and an energy-saving path, such as aleast-power-consumed link path. When a new path is chosen, the MS sendsa MAC message to the BS reporting the selected path list. This decisionmay also be made on a hop-by-hop basis by each RS, depending on howair-link QoS information is acquired, distributed and stored, eitherglobally or locally. It also depends on how radio resources are to beallocated and scheduled, for example centralized by the BS ordistributed amongst the RS.

In some embodiments the MS can apply MIMO technology to utilizemulti-path diversity. For example, several MS could transmit messagesusing collaborative MIMO (multiple input multiple output) techniques.

Route Maintenance

In some embodiments, any of the RS and/or MS periodically send RNG-REQmessages to the BS to test whether the existing routing paths are stillvalid. For example, the RS and/or MS sends a RNG-REQ message. If thepath is still valid the BS sends back a RNG-RSP (ranging response)message. If the path is not valid, that is there is no longer a directpath along that route, the BS will not receive the RNG-REQ and thereforenot send a RNG-RSP. In this case, the MS has to re-start network entryprocedure to re-attach to the BS and determine a new path to the BS.

Constraint-Based Dynamic Service Signaling

Reference to FIG. 3 will now be made in describing constraint-baseddynamic service signaling.

FIG. 3 illustrates the same example multi-hop network 200 that wasdescribed in FIG. 2.

When a path between the MS and the BS is known, transportationconnections are created between the BS and MS for transportation ofpayload data. For example, the path between the BS and a specific MS maybe known, but there is no data transportation or service flow currentlyoccurring over the path. In another example, that a service flow overthe path, but a further service flow is requested for the path. A firststep is to establish a service flow connection between the two stations.A transport connection can be created by the BS sending a DynamicService Addition request (DSA-REQ) defined in 802.16d to the MS via oneor more RS in the network or by the MS sending a DSA-REQ to the BS viaone or more RS.

In operation, a path list identifying nodes in the network is includedwith the DSA-REQ message. An example of such a path list is a path listselected by the MS and provided to the BS, which is based on theBS-oriented DSR discovery protocol. However, a path list that isdetermined by a method other than the BS-oriented DSR discovery protocol(e.g., a pre-provisioning path) can be included with the DSA-REQ. Thepath list is used by one or more RS between the MS and BS to navigatefrom the source of the DSA-REQ to the desired destination, that is fromthe BS to the MS or vice versa.

The following description is for describing constraint-based serviceflow provisioning on the path between BS 205 and MS 236, which isoriginated by BS 205. It is to be understood that a similar process canbe performed that originates from the MS and occurs in a reversedirection.

The BS 205 sends a frame with multiple bursts, each burst including oneor more MAC messages to the MS. In the example of FIG. 3, a DSx messageis part of a MAC message, indicated at 310 that includes a MAC header312, a MAC sub-header 316 and the DSx message body. The type of DSxmessage illustrated in FIG. 3 is a DSA message 320. The MAC header 312contains a management tunnel CID 314 field to identify that theconnection concerns a management related aspect of the link between BS205 and MS 236. The MAC header contains other fields as well that arenot shown. An example of other fields may be those shown in FIG. 4 anddescribed in further detail below. The MAC sub-header 316 includes apath list 318 that identifies the route between BS 205 and MS 236 as BS205

RS 212

RS 226

MS 236. The DSA-REQ message 320 includes a service flow ID (SFID) 322and a transport CID (Transport CID) 324. The transport CID can beconsidered a local CID between two stations for a single hop.

RS 212 receives the MAC message 310 and based on the path list 318determines that the MAC message 310 should be forwarded on to RS 226.The management CID 314 is used in conjunction with the path list 318 todetermine if any of the messages in the frame are to be dropped orforwarded. The management CID 314 of the message header 312 indicatesthat the MAC message 310 is directed to from BS 205 to MS 236. The pathlist 318 in the sub-header 316 for the MAC message 310 that is receivedby RS 212 includes both RS 212 and MS 236, so the MAC message 310 isforwarded over another hop to RS 226. Before the MAC message 310 isforwarded, the transport CID 324 is swapped, such that the MAC message310 becomes MAC message 310′ having a new local transport CID (TransportCID*) 330, which is the local CID for RS 212 to RS 226. RS 226 receivesthe modified MAC message 310′ from RS 212. RS 226 determines from thepath list 318 that the MAC message 310′ should be forwarded on to MS236. The transport CID 330 is swapped, such that MAC message 310 becomesMAC message 310″ having a new local transport CID (Transport CID**) 340,which is the local CID for RS 226 to MS 236. MS 236 receives themodified MAC message 310″ from RS 226.

Further details involved in swapping transport CIDs can be found inapplicant's corresponding U.S. patent application Ser. No. 11/478,719filed on Jul. 3, 2006, which is hereby incorporated by reference in itsentirety.

In some embodiments, instead of using transport CIDs specific toparticular station and swapping the transport CIDs for each hop, aglobal end-to-end transport CID can be carried in the DSx message. Inthis case, all the RS along the end-to-end path would simply forward DSxmessage to the destination MS, based on the path list from MACsub-header.

Based on operation of PMP downlink multicasting in 802.16, not all MACmessages in a downlink frame used to transport multiple MAC message aretargeted to the destination MS which is in a subordinate tree of aparticular RS. In some embodiments the particular RS drops the MACmessages not targeted to the destination MS. By checking the path listin MAC sub-header, or checking the CID ownership from a routing databaseand CID swapping table, the particular RS determines whether to continueforwarding the MAC messages or drop the MAC messages.

In the multi-hop architecture the BS may have a larger transmissionbandwidth capability than some or all of the RS. Therefore, droppingsome messages from a frame when navigating from the BS to MS via one ormore RS aids in mitigating bottlenecks in the network by moreefficiently utilizing bandwidth available to the RS.

The same process of constraint-based service flow provisioning can beused for other types of dynamic service signaling, for example asDSD-REQ (Dynamic Service Delete request) and DSC-REQ (Dynamic ServiceChange request). While the DSx message has been described as a specifictype of message that is used in the constraint-based service flowprovisioning, more generally the message may be described as a serviceflow request message.

More generally, in a multi-hop network comprising a base station and atleast one relay station, a method for message forwarding based on knownrouting paths between the base station and at least one non-relay mobilestation can be described as follows. The base station or a non-relaymobile station of the at least one non-relay mobile station sends over afirst hop a service flow request message including an end-to-end pathlist and a connection identifier (CID) that defines the connectionbetween the base station and the non-relay mobile station. Each relaystation of the at least one relay station receives the service flowrequest message that was broadcast over a preceding hop and determineswhether the message is to be forwarded over a subsequent hop or droppedbased on the path list and the CID. If the message is to be forwarded,the message is forwarded over a subsequent hop based on the contents ofthe path list and the CID.

In some embodiments of the constraint-based dynamic service signalingprotocol, IEEE 802.16 Dynamic Service Configuration messages (DSx, wherex=A, C, D for addition, change or delete, respectively) are used inconjunction with an end-to-end path list included in the MAC PDUsub-header. An example of such a sub-header is described in furtherdetail below. The constraint-based dynamic service signaling protocolenables CID forwarding path creation, CID path management and CID pathtear down for end-to-end paths. CID forwarding path creation provides amechanism for using an established path list when creating a new serviceflow between the BS and MS via one or more RS as described above. CIDpath management provides a mechanism for maintaining a forwarding tableat each RS to aid in routing flows as they pass through the RS. CID pathtear down provides a mechanism for cancelling service flows when pathlists have changed or become invalid as RS or MS relocate.

End-to-End CID Path Creation

In some embodiments, the BS or MS issues a DSA-REQ message to the nexthop and includes the path list in the modified mesh sub-header. The pathlist is used to navigate between a source station and a target station,that is BS to MS or vice versa, via the one or more RS. When each RSreceives the DSA-REQ message the RS determines whether to further relaythe message to the next hop or drop the message, based on the path listand management CID.

End-to-End CID Path Management

In some embodiments, when DSA-REQ/DSA-RSP (Dynamic Service Additionresponse) messages include an allocated transport CID, each RS createsan entry in a forwarding table. The entry may contain such details as anode identifier (node ID), a first local transport CID identifying alink to a station in a preceding hop, a second transport CID identifyinga station in subsequent hop, and the interface (I/F) ports associatedwith sending and receiving over hops of adjacent stations. If a globaltransport CID is allocated for end-to-end traffic by the BS, the firsttransport CID and the second transport CID are identical in theforwarding tables all the way from BS to RS and to MS. The forwardingtable is used for data flow relay. In some embodiments managementmessages carry the path list in a sub-header for navigation purposes.

Once stations have created forwarding tables, the respective stationscan conduct MAC layer forwarding functions such as service flow PDUforwarding and management flow PDU forwarding describe below.

End-to-End CID Path Release

In some embodiments DSD-REQ/DSD-RSP (Dynamic Service Deletion response)messages are also used to update CID allocation along the path.

For example, when the BS or MS decides to terminate a service flow, therespective BS or MS acting as a source node creates and issues aDSD-REQ. The MAC layer of the source node checks the CID of the serviceflow that is to be terminated against a service flow ID associated withthe service flow to be terminated, and creates the DSD-REQ with the CIDand the path list. The DSD-REQ is then transmitted to a RS over a firsthop by the source node. Each RS along the path receives and forwards theDSD-REQ along the path. After receiving the DSD-REQ each RS along thegiven route looks up the mapping table and removes the correspondententry. If the CID is allocated locally, it is returned to a local CIDpoll for future use. The DSD-REQ is forwarded until it reaches the laststation in the path list, which is a destination node. The destinationnode then sends a DSD-RSP back to the source node in acknowledgement ofthe DSD-RSP. DSD-REQ and DSD-RSP are defined in 802.16

In service flow PDU forwarding when the RS receives a MAC PDU from anode in the direction of the MS, the RS uses the CID associated with theMAC PDU and compares the CID with the forwarding table to determine ifthe RS should further broadcast the PDU to a RS in the direction of theMS (or the MS itself), or drop the MAC PDU. When the RS receives a MACPDU from a node in the direction of the MS, the RS forwards the MAC PDUto an RS in the direction of the BS (or to the BS itself).

In management flow PDU forwarding when the RS receives a MAC PDU from anode in the direction of the MS, the RS uses the CID associated with theMAC PDU and compares the CID with the forwarding table to determinewhether to process the MAC PDU, as the RS is a managed object, tofurther broadcast the PDU to a RS in the direction of the MS (or to theMS itself), or drop the MAC PDU. When the RS receives the MAC PDU from anode the direction of the MS, the RS forwards the MAC PDU to an RS inthe direction of the BS (or to the BS itself).

In some embodiments the air interface between the BS and RS is referredto as a Macro-PMP link and the air interface between the RS and MS isreferred to as a Micro-PMP link. The definition of Macro-PMP andMicro-PMP refers to distributed radio resource allocation andscheduling. In Macro-PMP, the BS allocates radio channels to all RScoupled to the BS over a first hop, and also allocates some blocks orpolls of radio frequencies or channels to some subordinate RS. In someembodiments the first hop RSs can further allocate radio channels fromthe BS allocated block/polls to subordinate trees of the first hop RSs.Such a second level allocation is referred to as Micro-PMP. Each PMPregion or cell defines a broadcast domain by given radio frequency orchannel. Via Macro-PMP and Micro-PMP, the end-to-end relay path can betreated as being composed of a concatenation of multiple PMP sub-pathswithin a multi-layer subordinate tree. In some embodiments each sub-pathwithin a sub-tree is logically represented as a tunnel. The tunnel canhave a corresponding tunnel CID. The tunnels can be used to supporttraffic aggregation, traffic security, traffic navigation and trafficQoS associated with Macro-PMP link and micro-PMP link.

FIG. 1B shows an example of a multi-hop network architecture includingBS 60 that has a Macro-PMP link with each of RS 62, RS 63 and RS 64. RS62 has a Micro-PMP link with each of MS 65 and MS 66. RS 63 has aMicro-PMP link with MS 67. RS 64 has a Micro-PMP link with each of MS 67and MS 68. In some embodiments the Macro-PMP links are used fortransmitting broadcast messages to some or all RS from the BS or fortransmitting messages to particular RS from the BS. In some embodimentsthe Micro-PMP links are used for transmitting broadcast messages to someor all MS from the BS via one or more RS or for transmitting messages toparticular MS from the BS via one or more RS.

FIG. 1B is one example of multi-hop network architecture. It is to beunderstood that the number of RS and MS in the network is implementationspecific and may vary from that shown in FIG. 1B. It is also to beunderstood that the number of MS connected to an RS is not limited to amaximum of two as shown in FIG. 1B, but the number of MS connected to anRS can be greater than two. Furthermore, a number of RS occurringbetween BS and MS can be greater than the one RS that is shown in FIG.1B. As shown in FIG. 1B, an MS can be coupled to more than on RS, forexample MS 67 connected to both RS 63 and 64, resulting in more than onepath from BS to MS.

In some embodiments, for the Macro-PMP link, the BS allocates radioresources for transmission to each RS and for receiving transmissionfrom each RS. In some embodiments, for the Micro-PMP link, the RSfurther partitions radio resources and allocates resources to the RS inthe direction of the MS. This is repeated for each RS located betweenthe BS and MS until resources are allocated for each MS. In someembodiments of the invention when allocating transmission resources,Macro-PMP and Micro-PMP schema share the same band and time slots whenusing MIMO transmission techniques, share the same band and time slotswhen using beam-forming transmission techniques, or the schema useadjacent band or different sub-channels.

In the multi-hop network architecture, the RS plays a double role. In afirst role, when interacting with the MS, the RS is a master thatactively coordinates with each MS the RS is associated with. In someembodiments this may include arranging cooperative MIMO transmission forcapacity enhancement or transmission diversity for coverage enhancement.In a second role, when interacting with the BS, the RS is a slave thatstores and forwards data packets to/from the BS.

In the multi-hop network architecture the BS has a fixed location. Insome implementations the one or more RS have a fixed locations. In otherimplementations the one or more RS is nomadic or mobile. The MS is fullymobile-enabled. However, in some embodiments the MS may be stationary.Mobile RS and MS may relocate within the same cell. Mobile RS and MS mayalso relocate to other cells having a different BS. When leaving onecell and entering another, handoff may be initiated by the BS, any ofthe RS or the MS.

In some embodiments data traffic is distributed to a next hop via PMPair link or multiple PP (point-to-point) air interfaces when sent in adirection from the BS to the MS. Each RS determines whether to furtherrelay the data flow along the path, or simple drop it.

In some embodiments data traffic from multiple stations, either relay ormobile is aggregated together at a next hop when sent in a directionfrom the MS to the BS.

In some implementations either one of or both of the BS-orientedprotocol and constraint-based signaling can be applied to a conventionalIEEE 802.16 relay-tree architecture and/or a conventional IEEE 802.16mesh architecture.

The frame structure used with some embodiments of the inventionsincludes MAP (multiplexing access profile) information elements (IE) toprovide a structure within the frame for defining where down link (DL)and up link (UL) transmission resources are located within the frame. ADL transmission resource is a time or frequency slot in the frameallocated for transmission from the BS in the direction of the MS, viaone or more RS. An UL transmission resource is a time or frequency slotin the frame allocated for transmission from the MS in the direction ofthe BS, via one or more RS.

By way of example, FIG. 4 shows a schematic diagram of a conventionalframe structure for time division duplex (TDD) transmission used inconjunction with embodiments of the invention.

Frame N, which is preceded by Frame N−1 and followed by Frame N+1,includes a DL sub-frame 105 and an UL sub-frame 108. The DL sub-frame105 includes a DL PHY PDU (packet data unit) 110 that has a preamble112, a frame control header (FCH) 114 and multiple DL bursts116,118,120. The FCH 114 contains the DL Frame Prefix (DLFP) 123 tospecify the burst profile and the length of the DL-MAP immediatelyfollowing the FCH. The DLFP is a data structure transmitted at thebeginning of each frame and contains information regarding the currentframe. In some embodiments the multiple DL bursts (1 to M) 116,118,120each have different modulation and coding. In other embodiments, some orall of the DL bursts have the same modulation and coding. A first DLburst 116 contains broadcast messages 124 to be broadcast to all RS andMS including DL MAP and UL MAP IEs (not shown). If the broadcastmessages 124 do not occupy an entire allocated time duration for thefirst DL burst 116, MAC PDU messages 126 directed to one or moreindividual MS may fill the remainder of the time duration. In someembodiments the broadcast messages may use more than a single DL burst.However, a shorter broadcast message means that more data and lessoverhead can be transmitted in the frame. Subsequent DL bursts 118,120include multiple MAC PDU messages (1 to P) 128,130 directed to one ormore individual MS. In some embodiments the DL bursts include padding132. Each MAC PDU message contains a MAC header 134. The MAC PDU messagemay also include a MAC message payload 136 and cyclic redundancy check(CRC) 138 as shown in FIG. 2. The CRC 138 is used for error detection.The broadcast messages 124 also contains a MAC header. Each MAC PDUmessage may also be assigned a sequence number that can be used forpurposes such as maintaining an ordered sequence at the receiver and/oraiding in retransmission of MAC PDU messages that were not received.

The UL sub-frame 108 shown in FIG. 4 includes a contention slot 150 forinitial ranging requests, which is a time duration for multiple MScommunicating with the BS to contend for time in finalizingsynchronization of the respective MS with the network. The UL subframe108 also includes a contention slot 152 for bandwidth (BW) requests,which is a time duration for the multiple MS communicating with the BSto contend for UL resources for transmission of data from the MS to theBS. The UL subframe 108 also includes multiple UL PHY PDUs 154,156 whichare the up link resources used by each respective source MS (1 to K) tocommunicate with the BS. Each UL PHY PDU 154,156 includes a preamble 160and an UL burst 162. The UL burst 162 is transmitted using a modulationand coding specific to the source MS. The UL burst 162 includes multipleMAC PDU messages (1 to P) 164,166. In some embodiments the UL burst 162includes padding 168. Each MAC PDU message 164,166 contains a MAC header170. The MAC PDU message 164,166 may also include a MAC message payload172 and CRC 174. Following the UL sub-frame 108 is a receive/transmittransition guard (RTG) 178.

FIG. 4 is an example frame that can be used in accordance with theinvention. In some embodiments the frame structure may not include allthe described components of FIG. 2, for example a frame structure maynot include both described contention slots, or may include additionalslots to allow contending for other reasons. Furthermore, a framestructure may have other additional guard slots such as atransmit/receive transition guard (TTG) located between the DL sub-frame105 and UL sub-frame 108. While the frame of FIG. 4 is substantiallyconsistent with the frame structure established for IEEE 802.16, the useof other frame structures may be considered within the scope of theinvention if capable of supporting the BS-oriented protocol andconstraint-based signaling as described herein.

In some embodiments frames N−1 and N+1 have a similar structure. Inother embodiments, frames in the sequence are a mixture of frames, somehaving a similar structure and others having different structure.

Frames enabling frequency division duplex (FDD) communication andcombined TDD/FDD communication are also both considered to be within thescope of the invention.

As described above MAC PDUs include MAC headers. The MAC header can beused to transmit data or MAC messages. There are two common forms or MACheader, a generic MAC header and a bandwidth request MAC header. MACPDUs may also contain a MAC sub-header that is typically locatedsubsequent to the MAC header.

802.16d MAC Sub-Header Extension

In 802.16d, a MAC PDU is composed of MAC header and MAC PDU body. TheMAC header is fixed in size while the MAC PDU body can be variable size.In the multi-hop architecture a route between the BS and MS includesmultiple hops via one or more RS. In some embodiments of the invention asub-header is provided that includes a node ID list, which is the pathlist of all the nodes along the selected path between BS and MS.

An example of a sub-header will now be described with regard to FIG. 5.Fields of a generic MAC header are collectively indicated at 400. Thenumbers in brackets in each field indicate a number of bytes in thefield.

The feedback header 400 includes a “Header Type (HT)” field 401, an“Encryption Control (EC)” field 402, a “Type” field 403, a “ExtendedSubheader Format Reserved (ESFRSV)” field 404, a “CRC indicator (CI)”field 405, an “encryption key sequence (EKS)” field 406, another “RSV”field 407, a “Length (Len)” field 408, a “CID” field 409 and a “HeaderCheck Sequence (HCS)” field 410. “HT” field 401 indicates the type ofheader. “Type” field 403 indicates sub-headers and special payload typespresent in the message payload. The “RSV” fields 404,407 are reservedfor variable use, which allows flexibility in the use of these fields.“Len” field 408 is the length in bytes of the MAC PDU including the MACheader and the CRC if present. In some embodiments values to be used inthe different fields can be found in the IEEE 802.16 standard.

When used with some embodiments of the invention, the CID field 409 inthe generic MAC header 400 is a tunnel CID. The tunnel CID can beconsidered a global CID between the BS and a specific RS or MS.Depending on whether the radio resource is allocated in a centralized ordistributed manner, in some embodiments the tunnel CID is allocated bythe BS and in some embodiments the tunnel CID is allocated by the RS. Insome embodiments the tunnel CID is a management tunnel CID that is usedfor signaling associated with managing a connection. In some embodimentsthe tunnel CID is a transport tunnel CID that is used for forwarding ofdata over a connection.

The sub-header is indicated at 415. The sub-header includes a listing ofn Node (or station) IDs that form the path list from the BS to a givenMS. The sub-header 415 is also shown to include fields for a CID Stack422, priority class 424, a Sequence number 426, and anair-link-descriptor 428. In some embodiments the air-link-descriptorincludes current radio channel and/or air link quality information. Insome embodiments the air-link-descriptor includes power consumptioninformation. In some embodiments the priority class field 424 containsan identifier that is used to determine the priority of contents of aforwarded message with respect to other forwarded messages. The priorityclass field allows the RS to prioritize the order for forwardingmessages.

In some embodiments the fields for CID Stack 422, priority class 424,Sequence number 426 and air-link-descriptor 428 are optional fields.Therefore, in some embodiments some or all of these fields may not beincluded in the sub-header.

For example, in some embodiments when the generic MAC header andsub-header are used for a Path Discovery Message, the sub-header mayinclude only the path list. In some embodiments the Path DiscoveryMessage may also include optional fields such as an air-link-descriptorand sequence number. As the Path Discovery Message is transmitteddownstream, for each new node, an identifier of that new node is addedinto path list of the PDM.

In some embodiments, when the sub-header is used in conjunction with aDSx signaling message, the sub-header may only contain the path list, tobe used for navigation purpose. In some embodiments, when the sub-headeris used for normal payload MAC PDU transmission, the sub-header maycontain CID stack and priority class information.

FIG. 5 is one example of a generic MAC header that those skilled in theart may be familiar with according to IEEE 802.16. In some embodimentsthere may be a greater or lesser number of fields in each of the genericMAC header and sub-header, respectively that that which are shown inFIG. 5. Furthermore, the MAC header fields may have a different numberof bytes than indicated in FIG. 5. More generally, it is to beunderstood that a MAC header having a different layout but performingsubstantially the same task could be used in conjunction with thesub-header.

FIG. 6 will now be used to describe an example of signaling flow betweenBS, RS and MS for entry of the RS and MS into the network, determinationof the path list, and PDU forwarding.

The RS enters the network either using a conventional PMP entry methodif the RS is adjacent to the BS or using a mesh entry method if the RSis not adjacent to the BS as indicated at 605. The MS enters the networkvia the conventional PMP entry method as it is adjacent to an RS asindicated at 607. The BS sends a path discovery message 610 to the RS asdescribed above as part of the path discovery protocol. The RS forwardsthe path discovery message 612 to the MS. The MS responds by sending thecompleted path list to the RS as a portion of a RNG-REQ (rangingrequest) message 615 and the RS forwards the RNG-REQ to the BS 617. TheBS sends a RNG-RSP (ranging response) to the RS 620 which is forwardedon to the MS 622 by the RS. While the main purpose of the RNG-RSP is forthe MS to connect with the network, it also acts to confirm the routingpath is correct between the BS and the MS. Step 630 shows a doublearrowhead line indicating that either the BS or the MS can act as thesource that initiates sending a DSA-REQ message to a destination forcreating an end-to-end flow path. At step 640 the destination then sendsa DSA-RSP to the source. At step 650 the source sends a DSA-ACK toacknowledge the DSA-RSP. Steps 660 and 662 illustrate implementationof 1) end-to-end management in the storing of information and 2) serviceand management flow PDU forwarding in the forwarding of MAC-PDU messagesin UL and DL directions.

In some embodiments the invention provides solutions for end-to-end datapacket delivery in a WiMAX (IEEE 802.16) tree and/or mesh networktopologies. In some embodiments the invention supports multi-hop relayfor data distribution/aggregation between BS and MS with tree and/ormesh topologies, which extends access coverage and achieves bettertraffic throughput and performance. In some embodiments the inventioncan be applied to fixed, nomadic and mobile RS relay topology.Furthermore, in some embodiments, aspects of the invention are backwardcompatible with existing IEEE 802.16d/16e standards with only a minorextension in the current interface definition.

In some implementations the invention is based on well-understood Ad hocnetwork routing technology and IEEE 802.16 dynamic service provisioningcapability. In some embodiments the multi-hop architecture can beapplied to both of multi-layer PMP radio tree and/or mesh networks andmultiple Point-to-Point air link tree and/or mesh networks.

In some embodiments the multi-hop architecture and associated protocolsused in conjunction with the architecture enable one or more of thefollowing benefits:

increased coverage of radio transmission and longer transmission range;

better utilization of radio resource allocation and reducedinterference;

enhanced system capacity and performance compared to known IEEE 802.16architecture and protocols;

improved MS battery life; and

lower cost system deployment.

Numerous modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practised otherwise than as specifically described herein.

1. A method of operating a base station in a multi-hop network,comprising: broadcasting a path discovery message (PDM) comprising: apath list comprising a node identifier for the base station; and abroadcast connection identifier (CID) identifying that the PDM isbroadcast for any non-relay station served by the base station; andreceiving a reply message from at least one non-relay station served bythe base station, the reply message comprising: a path list comprisingnode identifiers of the non-relay station and all stations in a routingpath between the base station and the non-relay station; and amanagement connection identifier (CID) identifying a managementconnection between the non-relay station and the base station defined bythe routing path.
 2. The method as defined in claim 1, wherein the stepof receiving a reply message comprises receiving the reply message viarelay stations identified in the path list.
 3. The method as defined inclaim 1, further comprising sending a service flow message comprising anend-to-end path list and the management CID that defines a connectionbetween the base station and the non-relay station.
 4. The method asdefined in claim 3, wherein the end-to-end path list comprises a list ofentries, each entry being one of a node identifier and a linkidentifier.
 5. The method as defined in claim 1, further comprising:receiving a request message from one of a relay station and a non-relaystation; and responsive to the request message, sending a responsemessage if a routing path to the non-relay station is still valid. 6.The method as defined in claim 1, further comprising allocatingtransmission resources for at least one relay station coupled to thebase station by a first hop.
 7. The method as defined in claim 1,wherein the base station operates in a manner consistent with any of:IEEE 802.16; IEEE 802.16d; and IEEE 802.16e.
 8. A method of operating arelay station in a multi-hop network, comprising: receiving a pathdiscovery message (PDM), the PDM comprising: a path list, the path listcomprising: a node identifier for a base station; and node identifiersfor any relay stations between the base station and the relay station;and a broadcast connection identifier (CID) identifying that the PDM isbroadcast for any non-relay station served by the base station; adding anode identifier of the relay station to the path list to generate anupdated path list; and broadcasting a PDM including the updated pathlist.
 9. The method as defined in claim 8, further comprisingdetermining whether a generated routing path is valid by: periodicallysending a request message to the base station; and receiving a responsemessage indicating that the routing path is still valid.
 10. The methodas defined in claim 8, further comprising: receiving a service flowrequest message comprising an end-to-end path list and a managementconnection identifier (CID) that defines a connection between the basestation and a non-relay station; determining whether the service flowmessage is to be forwarded or dropped based on the path list and themanagement CID; and if the message is to be forwarded, forwarding themessage based on the path list and the management CID.
 11. The method asdefined in claim 10, wherein the end-to-end path list comprises a listof entries, each entry being one of a node identifier and a linkidentifier.
 12. The method as defined in claim 8, wherein the relaystation operates in a manner consistent with any of: IEEE 802.16; IEEE802.16d; and IEEE 802.16e.
 13. A method of operating a non-relay stationin a multi-hop network, comprising: receiving at least one pathdiscovery message (PDM), the PDM comprising: a path list, the path listcomprising: a node identifier for a base station; and node identifiersfor any relay stations between the base station and the non-relaystation; and a broadcast connection identifier (CID) identifying thatthe PDM is broadcast for any non-relay station served by the basestation; and sending a reply message to the base station, the replymessage comprising: a path list comprising node identifiers of thenon-relay station and all stations in a routing path between the basestation and the non-relay station; and a management connectionidentifier (CID) identifying a management connection between thenon-relay station and the base station defined by the routing path. 14.The method as defined in claim 13, wherein the step of receiving atleast one PDM comprises receiving multiple PDMs, each having a differentpath list, from multiple relay stations, the method further comprising:determining which one of the multiple PDMs has a preferred path listbased on at least one criterion characterizing the path lists of themultiple PDMs; and selecting the PDM with the preferred path list to useas a routing path between the base station and the non-relay station.15. The method as defined in claim 14, wherein the at least onecriterion is selected from a group consisting of: shortest path betweenthe base station and the non-relay station; best determined radioperformance between the base station and the non-relay station;preferred value for at least one quality of service (QoS) parameter; andlowest power consumption for a link between the base station and thenon-relay station over the path.
 16. The method as defined in claim 13,further comprising determining whether a generated routing path is validby: periodically sending a request message to the base station; andreceiving a response message indicating that the routing path is stillvalid.
 17. The method as defined in claim 13, wherein the end-to-endpath list comprises a list of entries, each entry being one of a nodeidentifier and a link identifier.
 18. The method as defined in claim 13,wherein the non-relay station operates in a manner consistent with anyof: IEEE 802.16; IEEE 802.16d; and IEEE 802.16e.
 19. A base station foruse in a multi-hop network, comprising: a transmitter operable tobroadcast a path discovery message (PDM) comprising: a path listcomprising a node identifier for the base station; and a broadcastconnection identifier (CID) identifying that the PDM is broadcast forany non-relay station served by the base station; and a receiveroperable to receive a reply message from at least one non-relay stationserved by the base station, the reply message comprising: a path listcomprising node identifiers of the non-relay station and all stations ina routing path between the base station and the non-relay station; and amanagement connection identifier (CID) identifying a managementconnection between the non-relay station and the base station defined bythe routing path.
 20. The base station as defined in claim 19, whereinthe receiver is operable to receive a reply message by receiving thereply message via relay stations identified in the path list.
 21. Thebase station as defined in claim 19, wherein the transmitter is furtheroperable to send a service flow message comprising an end-to-end pathlist and the management CID that defines a connection between the basestation and the non-relay station.
 22. The base station as defined inclaim 21, wherein the end-to-end path list comprises a list of entries,each entry being one of a node identifier and a link identifier.
 23. Thebase station as defined in claim 19, wherein: the receiver is operableto receive a request message from one of a relay station and a non-relaystation; and the transmitter is operable, responsive to the requestmessage, to send a response message if a routing path to the non-relaystation is still valid.
 24. The base station as defined in claim 19,further comprising a transmission resource allocator operable toallocate transmission resources for at least one relay station coupledto the base station by a first hop.
 25. The base station as defined inclaim 19, wherein the base station operates in a manner consistent withany of: IEEE 802.16; IEEE 802.16d; and IEEE 802.16e.
 26. A relay stationfor a multi-hop network, comprising: a receiver operable to receive apath discovery message (PDM), the PDM comprising: a path list, the pathlist comprising: a node identifier for a base station; and nodeidentifiers for any relay stations between the base station and therelay station; and a broadcast connection identifier (CID) identifyingthat the PDM is broadcast for any non-relay station served by the basestation; a path list processor operable to add a node identifier of therelay station to the path list to generate an updated path list; and atransmitter operable to broadcast a PDM including the updated path list.27. The relay station as defined in claim 26, further operable todetermine whether a generated routing path is valid by: periodicallysending a request message to the base station; and receiving a responsemessage indicating that the routing path is still valid.
 28. The relaystation as defined in claim 26, wherein: the receiver is operable toreceive a service flow request message comprising an end-to-end pathlist and a management connection identifier (CID) that defines aconnection between the base station and a non-relay station; the pathlist processor is operable to determine whether the service flow messageis to be forwarded or dropped based on the path list and the managementCID; and the transmitter is operable, if the message is to be forwarded,to forward the message based on the path list and the management CID.29. The relay station as defined in claim 28, wherein the end-to-endpath list comprises a list of entries, each entry being one of a nodeidentifier and a link identifier.
 30. The relay station as defined inclaim 26, wherein the relay station operates in a manner consistent withany of: IEEE 802.16; IEEE 802.16d; and IEEE 802.16e.
 31. A non-relaystation for a multi-hop network, comprising: a receiver operable toreceive at least one path discovery message (PDM), the PDM comprising: apath list, the path list comprising: a node identifier for a basestation; and node identifiers for any relay stations between the basestation and the non-relay station; and a broadcast connection identifier(CID) identifying that the PDM is broadcast for any non-relay stationserved by the base station; and a transmitter operable to send a replymessage to the base station, the reply message comprising: a path listcomprising node identifiers of the non-relay station and all stations ina routing path between the base station and the non-relay station; and amanagement connection identifier (CID) identifying a managementconnection between the non-relay station and the base station defined bythe routing path.
 32. The non-relay station as defined in claim 31,wherein the receiver is operable to receive multiple PDMs, each having adifferent path list, from multiple relay stations, the non-relay stationfurther comprising a path list processor operable to: determine whichone of the multiple PDMs has a preferred path list based on at least onecriterion characterizing the path lists of the multiple PDMs; and selectthe PDM with the preferred path list to use as a routing path betweenthe base station and the non-relay station.
 33. The non-relay station asdefined in claim 32, wherein the at least one criterion is selected froma group consisting of: shortest path between the base station and thenon-relay station; best determined radio performance between the basestation and the non-relay station; preferred value for at least onequality of service (QoS) parameter; and lowest power consumption for alink between the base station and the non-relay station over the path.34. The non-relay station as defined in claim 31, further operable todetermine whether a generated routing path is valid by: periodicallysending a request message to the base station; and receiving a responsemessage indicating that the routing path is still valid.
 35. Thenon-relay station as defined in claim 31, wherein the end-to-end pathlist comprises a list of entries, each entry being one of a nodeidentifier and a link identifier.
 36. The non-relay station as definedin claim 31, wherein the non-relay station operates in a mannerconsistent with any of: IEEE 802.16; IEEE 802.16d; and IEEE 802.16e.